Perspective-drawing device



y Mardi 12, 1929 F. MARTINE-LLI ET AL 1,705s330 PERSPECTIVE DRAWINGDEVICE Filed April 18, 1928 Patented Mar. 12, 192,9.

raf-raar for-Fica FRANK MARTIN-ELM AND EDWIN Acker., or' NEW YoRK, N. Y.

PERSIECTIVE-DRAWING DEVICE.

This invention relates generally to drawing devices, and has moreparticular reference toa novel perspective drawing device. y

The invention has for an object the pro-V vision of device of the classmentioned, which is ot simple durable construction, desirable andeiiicient in operation, and which can be manufactured and sold at areasonable cost. i

The device proposes the use oi a base member provided with means forattachment on a drawing board and arranged for directing a T-square overthe board and towards a vanishing point or points oil of the board. Thebase is formed with grooveswhich are the arcsoif circles described frompoints along a common line, and preferably these grooves should benumbered for indicating the lengths vof the radii or diameters oi thecircles. A flexible member has its lower edge arranged Jfor engaging inanyy one ol the grooves i'orassumiiig the shape oit the particularGroove. This member projects above the liase and serves to guide theT-squa-re.

Any arrangement may be made for adapt ing the T-Vsquare to be guided bythe said flexible member. Since two points onthe arc of a circledetermine radial` lines of the circle,

the T-square may be provided with two rolll ers arranged for engagementwith the flexible member for correctly positioning the T-square. y

. In the making oil perspective drawings, all horizontal lines on eachplane ol any subject converge to a common center, technically known as avanishing point. It often, occurs that said vanishing points areestablished at various distances off the drawing board, inl

such instances it is necessary to employ the use of perspective curves.which are arcs, (usually of wood) cut to the desired radius. Thesecurves are tacked upon the drawing board and used with a perspectiveT-square whose end placed against the perspective curve forms a chord.This chord or T-square head has its contact points equidistant from thedrawing edge of the blade of the T-square. This drawing edge being aperpendicular and bisecting line o the arc, or ends of the T- square,produced will intersect the center of the circle of which theperspective curve is an arc. Obviously the moving of the T-` square headagainst the perspective curve will maintain its intersectingrelationship to `scription and accompanying drawings, and to theappended vclaims in which the various novel -features of the inventionare more particularly .set iorth.

In the accompanying drawing,.iorming a material part of this disclosure;Y l Fig. 1 is'a perspectiveview'ota drawing ooard provided with the saiddevice.

Fig. 2 is an enlarged face view of thedevice itself. f

Fig. 8 is ai'ragmentary enlarged vertical sectional view, taken on theline 3 3 of Fig. 2.

Fig. t is a similar viewkof a modified form of the device.

Fig. 5 is an enlarged sectional view, takenV on the line 5-.5 of Fig. 2.Fig. l is a 'fragmentary sectional view of the device andthe drawingboard and show-y ing the T-square applied thereto.v i i Fig. 7 isa'iragmentary perspective view oiy an ordinary T-square showing thebottom side thereof facing upwards.

The reference numeral 10 indicates generally a drawing board, andll aT-sqiiarc therefor. The particular type of drawing board and T-squareormsno limitation iny this invention. Y

A base member 12 preferably of rectangular shape is formed with cornercavities 13 in which tacks 14 are movably mounted. Apertures 15 arelorined in the base and the pointed members 16 ot the tacks may bemanually pressed thru these apertures for securing the base upon thedrawing board. The tacks are formed with raised edges 17 for engage mentby a persons finger nail for loosening the tacks from the drawing board.

- A plurality7 of grooves 18 are formed in the top surface of the basemember 12. These grooves are arc shaped, reference being had to a planview thereof, and are arcs of circles described from points along acommon line.

Numbers are provided adjacent eachgroove forstating the length oftheradii ofthe circles .from which the arcs are described, and thesenumbers are indica-ted by numeral 19 on the drawing. These groovesexten-d completely to the edges of the base member.

Fig. 3 shows these grooves of dove tailed construction, consideredtransversely, while Fig. 4 shows modified grooves 1S of bnlbed form.

A. flexible member 20 is constructed to slidably engage in the grooves18 at its 'top or bottom edges. Obviously this flexible member assumesthe curvature of the partie# ular gro-ove in` which it is placed. Aflexible member 20 is shown engaged in the grooves 18.

`The T-square shown in Fig. 1 is the usual perspective T-square in whichthe working edge 11 is equidistant from the two edges 11rL of the headof the T-square.

The Tsquare 11b shown in F 6 and 7 has a )air of verticall f arrangedrollers or pins 21 on its top side of the head thereof. These rollersare equally spaced from the drawing edge of the T-square. As shown inFig. 6 the rollers or pins 21 with 'lV-square, top side down may beengaged against the flexible member 20, and then the drawing edge of theT-square is directed to the center o1 the circle of the particulargroove 18 in which the flexible member is engaged, or in other Wordstoward a point which may be used for a vanishing point. The doll dashlines 22 in Fig. 1 show theT-square in this position. The T-square maybe moved along the flexible member, but will alwaysbe directed to thesame point. Y

In Fig. 1 the dot dash lines 23 indicate several of the Idevices placedtogether and aligned with their similar grooves so as to be usableas onedevice. Thus it is seen that the device may be ofsmall sections.

`While we have shown and described the preferred embodiment ofour-invention, it is to be understood that we do not limit ourselves lothe precise construction herein disclosed and the right is reserved toall changes and modifications coming Within the scope of the inventionas delined in the appended claims.

Having thus ldescribed your invention what we claim as newand desire tosecure by United States Letters Patent is:

1. In combination with a. drawing board and a T-square, a base securedto the draw' ing board, and formed with arc-shaped grooves representingthe arcs or' circles described from diierent points on a common line, a'lieXible member adapted to engage'in any one of the grooves forassuming its shape, and pair of abutinents on the head of the 'l'-squa1cenga-geable against the flexible member and arranged "r'or directing the'lsquare towards the center of the circle from which the arc isdescribed.

2. In a. drawing device, a base'securable to a d ravving board, and:forme-d Vwith arc-shaped `grooves representing the arcs of circles,different radii scribed from dill'erent points on a. common line, and aflexible member engageable in any of the grooves .for assuming its shapefor the purpose described.

3. In combination with a drawing board and a T-square, a base secured tothe drawing board, and formed with arc-shaped grooves representing thearcsv of circles of different radii, a -llexible member adapted to'engage in any one of the grooves for assuming its shape, and a pair ofabutments on the head of the T-square engageable against the ilexiblemember and arrangedv for'directing the T-square towards the center ofthe circle from which the arc is described.

l. In combination with a drawing board and a T-sqnare, a base secured tothe drawing board, and formed With arc-shaped grooves extendingcompletely to the edges and representing the arcs of circles describedfrom diii'erent points on a common line, a flexible member adapted toengage in any one of the grooves for assuming its shape by reason or'being slid in thru one end, and a pair of abutments on thehead of theT-square engageable against the flexible member andarranged fordirecting the T-square towards the center of the circle from which theare is described. y

In testimony whereof We have aliixed our signatures.

FRANK MARTINELLI. EDWIN ACKER

